feat: stream yolo at 4k

virtio-gpu exposes no NVENC/VAAPI, so sunshine software-encodes. Measured
x264 (superfast+zerolatency) on the 8 vCPUs: 73fps at 2160p against 135fps
at 1440p, so a 60fps client keeps roughly 20% margin.

Also brings the drifted agent-of-empires config upstream, which the
mutableFiles guard required before switching.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

home/yolo/monitors.nix

@@ -4,7 +4,11 @@ _: {
   # Matches every output rather than naming one: the virtio-gpu connector name
   # varies by qemu display backend (Virtual-1 vs Virtual-0). Explicit mode, not
   # `preferred` — this is the resolution Sunshine streams.
+  #
+  # 2160p is near the ceiling: virtio-gpu has no NVENC/VAAPI, so Sunshine falls
+  # back to x264, which measured 73fps here against 135fps at 1440p — a 60fps
+  # client has only ~20% margin.
   wayland.windowManager.hyprland.extraConfig = ''
-    hl.monitor({ output = "", mode = "2560x1440@60", position = "0x0", scale = 1 })
+    hl.monitor({ output = "", mode = "3840x2160@60", position = "0x0", scale = 1 })
   '';
 }